Do Hall Sensors need to be used to drive a Brushless DC Motor?
No, Hall sensors are only needed for feedback systems requiring a Hall Effect Sensor. A Brushless Motor may be sensorless where the back EMF is used to run the motor. However Hall Sesors are required when using Anaheim Automation's Brushless DC Controllers.

Helpful Information

How are BLDC Motor Products controlled
Most BLDC Motor Products need Brushless DC Controllers or drivers to run. There are many different types of Brushless DC Controllers that are manufactured around the world for different applications. Many come with different options and can be custom made. Most are referred to as Electronic Speed Controller (ESC).
In Brushless DC Controllers, either a Hall Effect Sensor or the Back EMF (Electromotive Force) is used to run the motor. The Hall Effect uses three hall sensors within the motor to help detect the position of the rotor. This method is primarily used in speed detection, positioning, current sensing, as well as proximity switching. The magnetic field changes in response to the transducer that varies its output voltage. A feedback is created by directly returning a voltage since the sensor operates as an analogue transducer. The distance between the Hall plate and a known magnetic field can be determined with a group of sensors, in this case, three, and the relative position of the magnet can be deduced. A Hall sensor can act as an on/off switch in a digital mode when combined with circuitry.
The Back EMF, also known as the Counter-Electromotive Force is caused by a changing electromagnetic field. In a BLDC Motor, the back EMF is a voltage that occurs where there is motion between the external magnetic field and the armature of the motor. In other words, the voltage is developed in an inductor by and alternating current or pulsating current. At every moment, the polarity of the voltage is the reverse of the input voltage. This method is commonly used to measure the motor's position and speed indirectly.

Theory of Brushless DC Controllers
Theory of Brushless DC Controllers
The speed of a brushless motor is directly proportional to the supply voltage, so when the supply voltage is reduced, so is the speed, and vice versa.
An example is, if your supply voltage is 12 volts and you decrease to 6 volts, then the speed will now run 50% slower than at 12 volts. Now, the question is, how can that be achieved when you have a battery or supply fixed at 12 volts?
Brushless DC Controllers work by varying the average voltage sent to the motor. It could do this by adjusting the voltage sent to the motor, but this is inefficient to do. A much more efficient way to do this is, to switch the motors supply on and off very quickly. When the switching is fast enough the brushless motor will only recognize the average effect. It will not notice that it is actually being switched on and off. The average speed of the brushless motor increases, as the amount of time that the voltage is on increases compared with the amount of time that it is off.
This on-off switching is performed by what is called a power MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). MOSFETs are devices that can turn very large currents on and off under the control of a low signal level voltage.
The time it takes a motor to slow down and speed up depends on the inertia of the rotor, how much torque and friction there is.

What are Brushless DC Controllers
Brushless DC Controllers (also known as Drivers) are devices used to run/control a Brushless Motor. They are also known as Speed Drivers and often referred to as Electronic Speed Control or ESC. Their main purpose is to "drive" the brushless motor, in other words make it run. There are many different types that are manufactured for different applications.
The main purpose of brushless dc controllers is to drive a brushless motor at a speed where a signal is taken that represents that demanded speed. If the speed of the brushless motor is measured, then it is a Feedback speed controller or also known as a closed-loop speed controller. If the speed isn't measured then it is called an open-loop speed controller. A feedback speed controller is more complicated than one that is not, but is much better and more efficient. Brushless motors come in a variety of forms, and the brushless dc controllers output will be different dependent on these forms.

How to select Brushless DC Controllers
When selecting brushless dc controllers for your motor, many things should be considered. What is your application? You will need to get specifics about the motor and the brushless dc controllers and compare them to see if they are compatible. Once you have figured all this out, you can then begin to compare different brushless dc controllers from different manufacturers.

Where are Brushless DC Controllers Used
Some applications that use brushless dc controllers are, but not limited to:

Appliances

Wheel encoders

Ice tray and dust box position sensing

Door and lid open/close detection

Low water indicator

Motor current monitoring and AC input current detection

Automotive ( High temperature and in cabin)

Lighting

Wiper systems

Airbag deployment systems

Brake systems

Displays and infotainment

Seat belt systems

Closure systems

LED lighting and Displays

Billboards

Backlighting (cameras, mobile phones, laptop PC's,etc.)

Illumination and signals

Office Automation

Printers

Fax machines

Shredder

Portable

Digital Camera

Mobile Phone

Choosing Brushless DC Controllers
There are very many features on Brushless DC Controllers but the hardest part is pairing up your Brushless DC Controllers to your brushless dc motors and figuring out if this pair will meet your expectations and get the job done. First you will pick a brushless motor and brushless dc controllers, then you will have to check the specifications for each of these and compare to the two to see if they will compatible with each other. You will need to do some research to get the best results.
You have to ask yourself what are the main features or options are you looking for in a brushless dc controllers? How much current are you outputting? How much voltage are you inputting? What do I need to control? These are some of the questions you might need or want to ask yourself before you buy a driver/controller that doesnt work with your motor. You need to know all of the motor specifications. What is the rated voltage and speed? How much current can the motor take or output? How much power is it rated for? Etc. Once you figure all of these things out you can now look for a driver/controller with similar or higher ratings.
There are many different types of BLDC Control products made today. Some companies make Brushless DC Controllers for specific applications there are also companies that make custom Brushless DC Controllers. What the controller does is directs the rotation of the rotor. In order for the controller to do this, it must somehow detect the location of the rotor. In some cases, encoders or hall effect sensors are used to measure the position of the rotor directly. Another approach is to measure the back EMF, in this case the hall effect sensors are not needed. These types of Brushless DC Controllers are also known as ?sensorless? drivers.
Remember much research should be done before buying a motor and brushless dc controller. If you want them to work properly and the way you need it to, research is necessary. I cant emphasize enough. There are many companies all around the world engineering Brushless DC Controllers to meet your needs for all different types of applications.

Required Maintenance for Brushless DC Controllers
Occasionally things go wrong with electronics. You should always make sure the environment of your brushless dc controllers is within specifications of the unit so that everything will run smoothly and consistently. The temperature, air, dust, and pressure play a big part in electronics. You always want to make sure those allow your brushless dc controllers to run and operate properly at all times. Those factors are almost always unpredictable and change all the time.

Lifetime of Brushless DC Controllers
The lifetime of brushless dc controllers should last you for a very long time, if not forever. That's if, and only if you are running within rated conditions. It is not best to run anything at its limits, that's why there are limits set. If you running your unit within or below rate conditions, you will not have to worry too much about checking in on it. It is always a good idea to check on your brushless dc controllers and their conditions. You never know with electronics, they can be unpredictable at times.

How Much do Brushless DC Controllers Cost
Brushless DC Controllers come in all different shapes and sizes. Brushless DC Controllers can be custom made and ordered from different manufacturers. Although there isn't a certain shape it, most Brushless DC Controllers have a rectangular or square shape to them. They can also come in very small packages as well as very big packages.
Brushless Motor Drivers consist of, but are not limited to:

PCB (Printed Circuit Board)

Transistors

Capacitors

Resistors

IC, Chips, microchips

Diodes

Potentiometers

Terminal Blocks/ screw terminals

Heat Sinks

LEDs

LCDs

Troubleshooting Brushless DC Controllers
When you are having problems with your Brushless DC Controllers there are multiple things to look for. Different units will have their own way of indicating a problem of fault within the Brushless DC Controllers. Most Brushless DC Controllers will have a fault light to help indicate a problem that has occurred. Some may have an "alarm" or noise of some sort.
Some problems that may occur, but are not limited to are:

There is always the possibility that something maybe shorted internally on the board. This is something you might not be able to fix by yourself. Most companies will have a warranty for the product which will allow you to send it back and get it properly fixed and tested.

Advantages and Disadvantages for Brushless DC ControllersThere are many advantages to using Brushless DC Controllers. They include the following, but not limited to:

History of Brushless DC Controllers
From the 1920s-1980s most electrically driven elevators used the Ward Leonard Brushless DC Controllers system. This control system has been used up until the early 21st century. Different variations were implemented into the Ward Leonard system, but were still called by the same name generally.
Electrical and mechanical adjustable Brushless DC Controllers and other new types developed after the Ward Leonard system was introduced. Electron tube types of Brushless DC Controllers began to develop in the 1920s, but electronic controls didn't begin to displace the Ward Leonard system until thyristor controlled drives were developed in the late 1960s. Ward Leonard's Brushless DC Controllers were rapidly becoming obsolete by the mid 1970s, but replacements for the existing Ward Leonard Brushless DC Controllers have continued until the beginning of the 21st century.

Applications
Brushless DC Controllers are used in a variety of applications in many different industries. Some of the applications are Appliances, Automotive, Aerospace, CNC, Consumer, Instrumentation, Medical, Packaging Equipment, and Semiconductor.